This invention relates to fire-alarm audible signaling systems and, more particularly, to a novel and highly-effective fire-alarm audible signaling system permitting selective communications and signaling between a central control station and a number of fire zones (in a high-rise apartment, for example, where each floor may be designated a separate zone).
U.S. Pat. to Klein et al No. 3,803,594, issued April 9, 1974, discloses digital interrogation of sensors in a fire alarm system from a central location. This system provides the advantage of economical wiring on the input side to the central location but in no way simplifies the wiring of the output side. Thus, on the output side, a separate pair of wires is still required from the fire-alarm control panel (FACP) transmitter to a receiver-driver in each zone, and, in a large system, a large and expensive amplifier is required. Conventional systems having only one pair of wires extending from the transmitter to the receiver-drivers in different fire zones typically lack the ability to activate the receiver-drivers selectively and to perform different functions in different zones. Another deficiency of conventional fire-alarm audible signaling systems is that their means for self-supervision does not sufficiently identify the location of a malfunction.